1. Field of the Invention
The present invention relates to a heat transfer apparatus. More particularly, the present invention relates to a loop heat pipe module and an evaporator thereof.
2. Description of Related Art
With the development of modern science and technology, light emitting diodes (LEDs) have been used as new illumination devices. As a large quantity of heat will be generated during the operation of the LEDs, and the luminance and reliability of the LEDs will be influenced apparently when the operating temperature is too high, the heat generated by the LEDs must be dissipated rapidly. In addition, with the innovation of semiconductor process technology, effective transistors in a unit area or volume of various chips increases gradually, which results in a dramatic increase of the generated heat despite of the improvement of the overall efficiency of the chips. When the operating temperature is too high, the stability and service life of the chips will be influenced. Therefore, the heat generated by the chips must be dissipated rapidly as well.
Referring to FIG. 1, in order to solve the problem of heat dissipation, U.S. Pat. No. 6,910,794 has disclosed a heat pipe 100 for dissipating heat. The heat pipe 100 includes a shell 110 and a porous member 120 disposed in the shell 110, and has an evaporation area 130 and a condensation area 140 disposed opposite to the evaporation area 130. The evaporation area 130 is adjacent to a carrier board 50, and a plurality of LEDs 60 is disposed on the carrier board 50. Volatile liquid is contained in the porous member 120. The heat generated by the LEDs 60 is conducted to the volatile liquid in the evaporation area 130 through the carrier board 50 and the porous member 120, so that the volatile liquid evaporates to become vapor. The vapor is then transmitted towards the condensation area 140, and passes through the porous member 120 to be dissipated into a gap 150 between the porous member 120 and the shell 110. The heat carried by the vapor in the gap 150 is dissipated to the environment, such that the vapor is condensed into the volatile liquid. Then, the condensed volatile liquid flows back to the evaporation area 130.
As the transmission distance and transmission direction of the volatile liquid in the heat pipe 100 are limited by the length and shape of the heat pipe 100, such a heat dissipation design cannot be applied to machines with various shapes, that is to say, the design flexibility is poor. Moreover, when the heat pipe 100 is placed vertically to make the condensation area 140 facing downward, the volatile liquid in the porous member 120 is concentrated in the condensation area 140 under the gravity, so the volatile liquid in the evaporation area 130 will decrease greatly, making the heat pipe unable to function normally and effectively.